Polymeric gentisamide antistain agents for color photography



United States Patent 'ice jjilffli? developing agent which is oxidized by the action of the 2,816,028 air. Fog or stain arising from these causes is not readily POLYMERIC GENTISAMIDE ANTISTAIN AGENTS controlled by the same procedures used to control silver FOR COLOR PHOTOGRAPHY a The incorporation of various compounds in photo- Louis Minsk, Rochesiel, a g or to Eastman graphic emulsions for controlling color fog or stain has Kodak p y: Rochester, u 3 cm1101'ation of been described in Weissberger and Vittum U. S. Patent New Jersey 2,356,486, August 22, 1944, and Vitlul'n and Wilder No Drawing Application July 29, 1955, U. S. Patent 2,360,290, October 10, 1944. However, the

serial 5 5 35 10 use of these simple reducing agents for preventing or controlling color fog or stain has a distinct disadvantage in 6 Clalms- (CL 96-100) that they have a tendency to wander from the areas in which they have been placed into other areas of the This invention relates to color photography and par- P g p Composition Where they have harmful ticularly to a method for preventing the formation of effects. In certain color processes the compounds are color fog 01- stain i photographic l ion placed in the area of the emulsion containing the coupler The method of color photography in which colorand act on it [0 P n r d BITB T forming or coupler compounds combine with the devel- It is, therefore, an ObjECt 0f the present invention (0 opment product of aromatic amino photographic develprovide a novel means for reducing or eliminating the opers to produce dyes i well k own, The olor former formation of color fog or stain in photographic emulsions. or couplers may be added directly to the emulsion layers A further object is to provide suitable non-diffusing reor may be incorporated in the developing solution as deducing agents for incorporation in Color photographic scribed in Fischer U. S. Patent 1,102,028, granted June materials. A further object is to provide a color form- 30, 1914, or they may be incorporated in a water-permeing photographic emulsion having non-difiusing couplers able medium which is insoluble in the carrier for the and non-dilfusing stain or fog inhibitors incorporated sensitive silver salt as described in Mannes & Godowsky therein. Other objects will appear from the following U. S. Patent 2,304,940, December 15, 1942, and Jelley description of my invention. and Vittum U. S. Patent 2,322,027, granted June 15, 1943. These objects are accomplished by incorporating in a A difficulty frequently encountered in these processes is Silver halide Emulsion Containing Color Couplers, a 11011- the formation of color fog or stain. When the exposed 3O diffusing polymeric compound having the structure 13 B -oH CH-: -CH- CH2CH CH- (IJOOH 50011 I (50011 50 x A i-[omn-rvuco-O material is developed in a color forming developer, dye in which A is hydrogen, an alkyl radical, e. g., methyl or fog is frequently formed in the emulsion layer. This is ethyl, or a halogen atom, e. g., chlorine, B is hydrogen or because the developing agent has been oxidized to some an alkyl radical, e. g., methyl or ethyl, Z is an oxygen extent by the action of the air and the oxidized developer atom or NH, 11 is a positive integer of 1 to 6, and tends to couple with the color-forming compound at x and y are positive integers, for example, from places in the photographic material where no silver image to 2000. is produced. it is well known that in these processes the Instead of the styrene unit, the polymer may have a dye should be formed only where the silver halide is vinyl butyl ether unit or an acrylic acid unit, as illusreduced to metallic silver, thereby oxidizing the developtrated below. ing agent to a form which couples with the color former. The antistain agents which I propose to use are pre- Once the developing agent is oxidized, it couples irnmepared by the reaction of a styreue-maleic anhydride interdiately with the color former whether a photographic 50 mediate and a derivative of gentisamide. The preparaimage is present or not. Aerial oxidation of the develtion of the styrene-maleic anhydride intermediate is deoper or oxidation by means other than development of scribed in Godowsky U. S. Patent 2,698,794. the photographic image therefore converts the developer The following compounds are suitable for use accordto a form which will immediately react with the color ing to my invention.

$0011 boon c0011 b0 o-omomuuco 11 former to produce a color fog or stain. This elfect is This compound was prepared by the reaction of a especially noticeable in materials having couplers incorstyrene-maleic anhydride intermediate and bl-ii-hyrlrex porated in the sensitive emulsion layer since there is no ethylgentisamide. In the preparation, water is ultimately coupler in the developing solution to react with any added to open any residual anhydride.

-OHrGH-CHCH CHr-CHCH--CH (EOOH (300R (SOOH $0 This compound was prepared by the reaction of a bility of the coupler in the emulsion, either to heat or styrene-maleic anhydride intermediate with N-fl-aminoto visible or ultraviolet radiation should not be decreased cthylgentisarnide. by added agents and it is found that my compounds an:

(j: 5 H 00H 00H OOH 0 i I 4H: NH CHzC HINHC 0 This compound was prepared by the reaction of a helpful in this respect also. In mixed packet systems it vinyl butyl ether-maleic anhydride interpolyrner with is also desirable to improve color separation between the N-fl-aminoethylgentisamide. packets and my compounds are of use for this purpose.

-GH CH-OH--CH OHrGH-CHCB I I I g 011 COOH OOH OOH IC NHCHzCHsNHCO CH; CH; 1/

This compound was prepared by the reaction of a vinyl The following examples illustrate the way in which my toluene-maleic anhydride interpolymer with N-fi-arninocompounds may be used. ethylgentisamide. a

(5) Reaction product of styrene-itaconic anhydride in- EXAMPU: I terpolymer and N-B-aminoethylgentisamide. This example shows the improvement in stain and (6) Reaction product of dichlorostyrene-maleic an- "print-out achieved by the use of my compounds. Stain hydride interpolymer and N-B-aminoethylgentisamide. was measured by determining at various wave-lengths the (7) Reaction product of styrene-citraconie anhydride reflectance of an unexposed, processed emulsion coated interpolymer and N-B-aminoethylgentisamide. on a reflecting cellulosic support. Comparison of this re- H-C H CH CHCH CH- OOH 00H 00H 0 NHCHICHBNHOO This compound was prepared by the reaction of polyflectance with that obtained for uncoated support indiacrylic anhydride and N-fl-amiuoethylgentisamide. cated the effectiveness of the agent being tested, the re- (9) Reaction product of styrene-maleic anhydride intersults being expressed as a percentage of the reflectance polymer and N-B-hydroxyethylhomogentisamide. of the uncoated support. Print-out or stability to 10) Reaction product of styrene-maleic anhydride invisible and ultra-violet radiation, was measured as loss in terpolymer and N-y-aminopropylgentisamid percent transmittance of the unexposed processed sample My compounds are useful in silver halide emulsions 5011- before and after 6 hours exposure in the Fade-O-Meter.

taining color couplers of the type which couple with the A solution of 4 grams of the coupler 2-(2,5-diamyloxidation product of primary aromatic amino developing phenoxyacflflmmo) 4,6 dlChlOfO 5 mfilhylphwol and agents. My compounds can be used in emulsions of the Varying flmflllnts 0f C mp und I in 10 cc. of di-n-butyltype in which the coupler is incorporated directly in the Phthalate was Prepar d by heating a mixture of the comgelatin in the form of a water-soluble but non-diffusing Punenls to The hot solutions r each poured Compound i hi h th gouple i di l d i an with stirring into 160 cc. of an aqueous solution oi 30 organic solvent before dispersion in the emulsion as def 1 gelatin solution and 4 cc. of 5% ethanol ll scribed in Jelley and Vittum U. s. Patent 2,322,027, or Solution (sodium pr pylnaphthalene sulfonate). in mixed packet systems of the type described in Godowh @Suhing i were each l'ecycled g 1 C0 sky U. S. Patent 2,698,794. My compounds are usually for 5 mmutes, and the Faulting fills dispfilsivm 30 were each mixed with 100 grams of a melted gelatinosilver bromide emulsion. The mixtures were then coated on White pigmented film support and dried. After exposure to a density scale and processing in a diethyl-p-- phcnylenediamine developer, the samples were fixed and employed in amounts ranging from 0.5% to 20% of the amount of coupler used in the emulsion although more or less of the polymeric anti-stain agent may be employed as desired or necessary. My compounds have the capacity to form and when used m the Godowsky System 65 stain and print-out were determined as indicated above. probably occur 111 the packet phase. with the following results.

My agents may be used to improve various properties H. of photographic emulsions containing couplers. Stain Stain, Printout in the emulsion due to the reaction between coupler and mp u d 1, g am per sci-ft. Raolfifieagglce Refiectnncu oxidized developer formed either by aerial oxidation or I ..s by the processing solutions may be reduced in certain Pam, Fermi cases by the use of my compounds. Stability of the dye 5 resulting from color development should not be impaired 33 2 by agents added to the emulsion and experiments show 5- that my compounds are satisfactory in this respect. Sta- Increasing stain reflectance indicates a reduction in stain, and decreasing print-out reflectance indicates a decrease in print-out, as the concentration of antistain agent is increased.

EXAMPLE 2 This example was the same as Example 1 except that instead of the cyan coupler of Example 1 there was used 4 grams of the coupler N-(4-benzoylacetaminobenzenesulfonyl)-N-(' -phenylpropyl)-p-toluidine. After processing the unexposed coating as in Example 1, stain and printout were determined as in Example 1 with the following results:

EXAMPLE 3 Separate emulsion coatings were made as in Example 1, using 1, 5 and 25 mg. per sq. ft. of compounds 3 to 10. After exposure to a density scale and processing in a diethyl-p-phenylenediamine developer, the samples were fixed, and the amount of stain in the unexposed regions, and the amount of dye loss, were determined. To determine stain, the cyan dye density in unexposed regions was read through a Wratten No. 25 filter, before and after exposure for 6 hours in a Fade-O-Meter. Cyan dye loss was determined by reading the cyan dye density before and after exposure in the Fade-O-Meter, and calculating the percentage loss. For comparison purposes, samples containing no anti-stain agent, and containing 1 and 5 mgs. of 2,5-di-tert. octyl hydroquinone, were treated in the same way. The results were as follows:

Stain Cyan dye loss Sample (Six-hour Fresh Incu- FadeO- bated Meter) Percent None 265 28 5. 1 Dioctyl hydroqulnone: 225 2. 6

. 205 25 2. 7 15 215 5. 3 25 mg 125 145 5. 4 Compound 4:

1 mg .22 .305 4. 9 5 mg.. 17 24 6. 1 25 mg. .145 .175 5. 4 Compound 5:

EXAMPLE 4 This example shows the improvement in stain and printout achieved by the use of my compounds in a packet system.

A cyan coupler dispersion was made by dissolving 4.3 grams of the cyan coupler used in Example 1 in 5 cc. of n-butylphthalate at 150 C., adding the solution to 5 cc. of a 5% solution of alkanol B dispersing agent in 25 cc. of 10% gelatin solution and dispersing it therein.

Six grams of a red-sensitive gelatino-silver bromoiodide emulsion were added to 8 grams of the cyan coupler dispersion and mixed with a fast stirrer for 10 minutes. Twelve cc. of a 10% solution of a copolymer of methacrylic acid and methyl-a-methacrylate (sodium salt) were mixed with cc. of distilled water. The emulsioncoupler dispersion was added to the copolymer solution and this was stirred for 10 minutes more. To this mixture there was added a mixture of 4 cc. of a 2.5% solution of the ammonium salt of styrene-maleamic acid polymer and 4 cc. of a 2.5% solution of the sodium salt of compound 3 and the whole dispersion was stirred at 42 C. for one hour. Then 50 cc. of an 18% gelatin solution were added and mixed. The resulting packets contained 10 g. of compound 3 per mole of silver.

A similar emulsion was made without the antistain agent and both coatings were exposed and developed, and

This example shows the improvement in dye stability achieved by the use of my compounds. Stability of the coupled dye to visible and ultra-violet radiation was determined by measuring the loss in density of the dye at its maximum spectral absorption, after exposure in the Fade- O-Meter for comparable periods of time, as in the preceding examples.

A dispersion of the cyan coupler of Example 1 was made as described in Example 4, containing sufiicient 2,5- di-tert.-octyl hydroquinone to give 0.5 mg. per square foot in the resulting coating. This dispersion was mixed with a red-sensitive gelatino-silver halide emulsion and packets formed as described in Example 4. This coating was designated A."

A similar dispersion was made without the dioctyl hydroquinone and was mixed with a similar dispersion in equal amount, of an emulsion containing the magenta coupler l-(p-tert. butylphenoxy)-phenyl-3-a-(p-tert. butylphenoxy propionylamino) 5 pyrazolone. This mixed emulsion was coated and designated B.

A mixed emulsion of cyan and magenta coupler similar to B was made but containing in the cyan packets sufiicient 2,5-di-tert. ootyl hydroquinone to give 50 mgs. per square foot in the resulting coating. This mixed emulsion was coated and designated C.

A mixed cyan and magenta packet coating similar to C was made but containing instead of the dioctyl hydroquinone, sufiicient styrene-maleic acid-gentisamide antistain agent (compound 1) to give 14 mgs. per square foot of the resulting coating. This mixed emulsion was coated and designated D.

Each of the coatings were exposed on an Eastman type Ib Sensitometer and was then developed for 10 minutes at 68 F. in the following developing solution:

Grams 2-amino-5-diethylaminotoluene, HCl 2 Sodium sulfite 2 Sodium carbonate, monohydrate 20 Potassium bromide 2 Water to 1 liter.

After fixing, washing and bleaching each of the coat tags to remove residual silver and silver halide the coat- Coating Density Loss l i A J 0.5 rug/sq. it. dioctyl liydroqu'mone l l4 None". .04 50 mgysq. ft. dioetyl hydroqulnone ttttt .18 ll Lug/sq. it. Compound 1 0.04

The loss in density of the cyan dye is shown to be much less than when clioctylhydroquinone (a prior art antistain compound) is used in the coating and is slightly less than when no antistain agent at all is used in the coatting. At the same time the color separation in a mixed packet system was found to be improved by the use of my compound.

The compounds of my invention were prepared as follows:

Compound l.Sryreuemaleic m1hydride-N-fl-hydr0xyethyl genrisamide in an all-g|ass reflux outfit equipped with a mechanical stirrer and calcium chloride tube to keep out moisture, 50 g. of styrene-maleic anhydride interpolymer was dis solved in 500 ml. of dry pyridine. When doping was complete. 55 g. of N-fi-hydroxyethylgcntisamide was added and the reaction was heated on a steam bath with Stirring for two hours. Twenty-five milliliters of water was then added and heating was continued for an additional hour. The dope was poured into 8 liters of ether, with stirring. The precipitate was allowed to settle, the supernatant was decanted and replaced by 3 liters of fresh ether. The soft precipitate turned friable. It was filtered onto a Biichner and given three extractions with 3-liter portions of fresh ether. mechanically stirring for at least one hour and filtering after each. The friable product was dried in a vacuum desiccator under a constantly applied water pump vacuum. The yield was 115 g.; the nitrogen content, 3.8%; the hydroquinone equivalent. 36.7% (see below).

Compound 2.-.Styrene-mnleic unhydride-N-B-aminoethyl gentisnmidc A. THE PREPARATION OF N-B-AMINOETHYL- GENTISAMIDE With mechanical stirring, 168 g. of methyl gentisatc was added to 800 ml. of ethylenediamine over a 15- minute period. The temperature of the reaction mixture rose spontaneously to about 60 C. Stirring was continued for 4% hours during which the reaction returned to room temperature. The excess ethylenediamine was removed under reduced pressure and the residue was boiled with a solution of 1 liter of benzene and 400 ml. of absolute ethyl alcohol. With stirring, the oily residue changed to a crystalline solid. The crystals were filtered onto a Bi'tchner funnel, washed on the funnel with a solu tion of 500 ml. of benzene and 200 ml. of absolute ethyl alcohol, and dried in a vacuum desiccator over calcium chloride under a constantly applied water pump vacuum. The crude material was recrystallized from 60-40 ethyl alcohol-water and redried as above. The yield ranged between 121 and 126 g. The melting points of different batches ranged from 194.5 to 196 (with decomposition). The nitrogen content was theoretical.

B. REACTION OF STYRENE-MALEIC ANHYDRIDE IN- TERPOLYMER AND N B-AMINOE'LHYLGENTISAMIDE Fifty grams of styrene-maleic anhydride interpolymer was dispersed in 500 ml. of dry pyridine at 50 C. under dry nitrogen in an all-glass outfit equipped with mechanical stirrer, gas inlet, and reflux condenser protected from moisture by calcium chloride tube. To the dope was added 155 g. of NyS-aminoethylgentisamide and the heating and stirring at 55 C. under dry nitrogen was continued for 4 hours, when ml. of distilled water was added and the reaction was heated for an additional hour. The dope was then poured into a stirred solution of 5 gal. of distilled water and 750 ml. of concentrated hydrochloric acid. The precipitate was stirred until nicely friable and filtered onto a Biichner tunnel. The product was washed on the funnel with distilled water and then stirred for 15 minutes in a container with two successive lO-liter portions of distilled water, filtered onto a funnel after each. Most of the water was removed by drying in a vacuum desiccator over calcium chloride under a constantly applied water pump vacuum. The damp material was dissolved in 700 ml. of absolute ethyl alcohol, 5 g. of zinc dust was added, and the solution was brought to a boil. Concentrated hydrochloric acid was added slowly until the evolution of hydrogen began (sa 8 ml.) when 5 g. more of zinc dust was added, followed by 5 ml. of concentrated hydrochloric acid. The reaction was allowed to proceed until no further decolorization occurred. The dope was then filtered through paper and precipitated after dilution by absolute ethyl alcohol to a volume of 1 liter, by pouring into 10 liters of stirred distilled water. The precipitate was filtered, washed on the funnel with dis tilled water, and stirred for 30 minutes in a beaker with two 3-liter portions of distilled water, filtering after each. The product was dried in a vacuum desiccator over cal cium chloride under a constantly applied water pump vacuum. The yield was 86 g.; N:6.2%; hydroquinone equivalent, 39.9%.

Compound 3.-Butyl vinyl ether-maleic anhydride-N piaminoethylgcntisamide Ten grams of vinyl butyl ether-maleic anhydride inter polymer was dispersed at 50 C. under nitrogen in 100 ml. of dry pyridine in an all-glass reflux outfit equipped with a mechanical stirrer. A smooth, deep violet dope was obtained. Eleven grams of N-fl-aminoethylgentisamidc was added and the reaction was maintained at 50 C. under nitrogen with continuous stirring for five hours. Twenty-five milliliters of distilled water was added and the reaction mixture was stirred for an additional hour at 50 C. The dope was then diluted with 25 ml. of acetone and was poured in a fine stream into a stirred solution of ml. of concentrated hydrochloric acid in 3 liters of distilled Water. The precipitate obtained was washed with distilled water until free from acid and dried in a vacuum desiccator under a constantly applied water pump vacuum. The dry material was dissolved in 250 ml. of 10:1 by volume absolute ethyl alcohol: distilled water and heated on a steam bath with mechanical stirring. To the hot stirred dope was added 10 g. of zinc dust, followed by 7 ml. of concentrated hydrochloric acid. With the evolution of hydrogen, the color of the dope was bleached to a light yellow. The dope was filtered by suction through paper covered by a layer of filter aid and precipitated in 3 liters of distilled water containing 75 m1. of concentrated hydrochloric acid. The product was washed free from acid with distilled water and dried as above. The yield was 15 g; N=6.6%; hydroquinone cquivalcnLZ-i-E9i.

Compound 4.-Vinylt0luene-malcic anhydride-N-fiaminoethylgentisamide =6.7% nitrogen and had a hydroquinone equivalent of 9 Compound 5.Styrene-itaconic anhydride-N-paminoethylgentisamide The procedure and proponions were similar to those used for the reaction with the vinyl butyl ether-maleic anhydride interpolymer (compound 3), except that the zinc reduction step was omitted. The yield was 16 g. The nitrogen content was 6.4% and the hydroquinone equivalent 39.0%.

Compound 6.Dichlorostyrene-maleic anhydride-N-B- aminoethylgentisamide The procedure used was similar to that for the vinyltoluenemaleic anhydride interpolyrner reaction (compound 4), except that double quantities were used. The yield was 26 grams. The nitrogen content was 4.0% and the hydroquinone equivalent 21.5%.

Compound 7.-Styrene-citraconic anhydride-N-flaminoethylgentisamide The reaction conditions and proportions used were similar to those used for the dichlorostyrene-maleic anhydride reaction (compound 6), except that the product was further purified by another reprecipitation from acetone into water and hydrochloric acid followed by washing acid-free. The yield was 32.5 g. The nitrogen content was 6.5% and the hydroquinone equivalent 32.9%.

Compound 8.Polyacrylic anhydride-N-fl-aminoethylgentisamide In an all-glass reflux outfit equipped with reflux and calcium chloride tube, a mechanical stirrer and a gas inlet, 10 g. of polyacrylic anhydride was dispersed under dry nitrogen at 50 C. in 100 ml. of dry pyridine. To the dope was added 18 g. of N-fl-aminoethyl gentisamide and the reaction was continued with stirring at 50 C. After 2 hours, an additional 50 ml. of pyridine, and, after /2 hours, 25 ml. of distilled water were added and heating and stirring continued for another hour. The dope was diluted with 100 ml. of acetone and poured in a fine stream into 3 liters of distilled water containing 225 ml. of concentrated hydrochloric acid. The rubbery precipitate was kneaded with fresh distilled water and then redissolved in 250 ml. of acetone. It was reprecipitated in 3 liters of distilled water containing 75 ml. of concentrated hydrochloric acid, washed with fresh distilled water until free from chloride, and dried in a vacuum desiccator over calcium chloride under a constantly applied water pump vacuum. The material with drying became brittle and could be ground. The yield was 11.0 g. The nitrogen content was 7.8% and the hydroquinone equivalent was 46.8%.

Compound 9.-Styrene-maleic anhydride-N-fl-hydroxyethylhomogentisamide A. THE PREPARATION OF N-B-HYDROXYETHYLHOMO- GENTISAMIDE Thirty grams of homogentisic lactone was added portionwise to a solution of 13.2 g. of ethanolamine in 100 ml. of methyl alcohol. There was some spontaneous warming. The reaction mixture was left at room temperature for one day. The methanol was then distilled away and the residue was dissolved with warming in 75 ml. of distilled water. After being made acid to Congo red with hydrochloric acid, the solution was successively treated with decolorizing carbon (Norite), filtered, and boiled with zinc dust. This removed most of the color. The solution was again made acid with hydrochloric acid, chilled, and filtered to remove a small amount of homogentisic lactone which crystallized out. The filtrate was concentrated at room temperature by vacuum to a syrup, and chilled. A slurry of crystals formed. The crystals were filtered onto a Biichner funnel, washed with a small amount of cold water, and dried in vacuum. Upon recrystallization from 2:1 abso- 10 lute ethyl alcohol: ligroin and drying, the product melted at 1175-1185 C. The yield was 12 g.

Analysis.-Calculated for N-fl-hydroxyethylhomogentisamide (C1QH1304N): C, H, N, Found: C, 56.9%; H, 6.3%; N, 6.6%.

B. REACTION OF STYRENE-MALEIC ANHYDRIDE IN- TERPOLYMER AND NB-HYDROXYETHYLHOMOGEN- TISAMIDE Five grams of styrene-maleic anhydride interpolymer was dispersed in 50 ml. of dry pyridine in an all-glass reflux outfit equipped with a mechanical stirrer and protected from moisture by a calcium chloride tube. To this was added, with stirring, 6.0 g. of N-fl-hydroxyethylhomogentisarnide and the reaction mixture was heated on a steam bath for one hour. Two and one-half milliliters of distilled water was then added and heating and stirring was continued for another hour. The dope was then cooled, diluted with ml. of acetone and poured into 1500 ml. of ether with stirring. The precipitate was thoroughly extracted with ether and dried in a vacuum desiccator under a constantly applied water pump vacuum. The yield was 8.4 g. The nitrogen content was 3.1% and the hydroquinone equivalent was 24.0%.

Compound 10.Styrene-maleic anhydride-N- yaminopropylgentisamide A. THE PREPARATION OF N-7-AMINOPROPYLGEN- TISAMIDE Ten grams of methyl gentisate was added to 45 g. of l,3-diaminopropane. Some heat was evolved. The flask was tightly stoppered and left at room temperature for one hour, during which time the reaction mixture changed to a slurry of crystals. This was diluted with 75 ml. of 5:2 benzene:absolute ethyl alcohol. The crystals were washed on the funnel with benzene-absolute ethyl alcohol (5:2) and dried. The product was recrystallized first from ethylene glycol monomethyl ether and then from absolute ethyl alcohol and water (55:45). This yield was 7 g.; melting point 209-210 C. (decomp.).

Analysis.Calculated for N-v-aminopropylgentisamide c u o ruy C, 57.1%; H, 6.7; N, 13.3%. Found: C, 56.8%; H, 7.0%; N, 13.4%.

B. REACTION WITH STYRENE-MALEIC ANHYDRIDE INTERPOLYMER The procedure used was quite similar to that used for the reaction of styrene-maleic anhydride interpolymer and N-fl-aminoethylgentisamide. Five grams of styrene maleic anhydride interpolyrner was dispersed at 50 C. under nitrogen in 50 ml. of dry pyridine in an all glass outfit equipped with reflux condenser and calcium chloride tube, mechanical stirrer and gas inlet. Six grams of N-y-aminopropylgentisamide was added and the reaction mixture was stirred for 3 /2 hours at 50 C. Two and one-half milliliters of distilled water was added and, after 4 hour, additional warming and stirring, the dope was diluted with 50 ml. of acetone and poured into 1.5 l. of distilled water containing 75 ml. of concentrated hydrochloric acid. The precipitate was filtered onto a Biichner funnel, washed on the funnel with distilled water and stirred ten minutes each with two 750-ml. portions of distilled water, filtering after each. The product was dried in a vacuum desiccator over calcium chloride under a constantly applied water pump vacuum. The yield was 9.0 g. The nitrogen content was 6.2%; the hydroquinone equivalent was 39.2%.

My stain inhibitors are particularly useful with paper materials where it is important to reduce the minimum or fog densities. This applies both to negative developing paper and to reversal paper. My stain inhibitors may. of course, also be used with transparent materials.

I have described the preparation of my anti-stain agents from gentisamide derivatives such as N-p-hydroxyethyl gentisamide. Homogentisarnide derivatives may also be used, such as N-fi-hydroxyethyl homogentisamide and N- B-aminoethyl homogentjsamide, in the preparation of my class consisting of hydrogen and alkyl radicals, Z is secompounds. lected from the class consisting of O- and -NH-, Vehicles other than gelatin may be used in the emulx and y are positive integers from 50 to 2000, and n is a sions in which my antistain agents are incorporated, e. g., positive integer from 1 to 6. polyvinyl alcohol, casein and its derivatives, gelatin deriva- 5 2. A color-forming photographic emulsion having retives, water-permeable cellulose derivatives, polyacrylduccd fogging tendency, comprising a silver halide emulamides, polyvinyl acetals or mixtures of these with gelatin. sion having incorporated therein a non-diffusing color It will be understood that the examples and modificacoupler capable of reacting with the oxidation product tions disclosed herein are exemplary only and that my of a primary aromatic amino developer to produce a dye invention is to be taken as limited only by the scope of and. as an inhibitor of color stain, a non-diffusing polythe appended claims. mcric compound having the structure:

1|; B -CH2-CHC CH CHzCH( J CH- l l l A 6 OH COOU GUOH 00H iO A A Z[CH2],,-NHC0- x (HI I claim: where A is selected from the class consisting of hydrogen, 1. A color-forming photographic emulsion having realkyl radicals, and halogen radicals, B is selected from til-166d i! tendency, P g Z1 Sliver hal de emulthe class consisting of hydrogen and alkyl radicals, Z sion having incorporated therein a non-difi uslng color is Selected f the Class consisting of and coupler capable of reacting with the oxidation product x and y are positive integers from 50 to 2000, of a primary aromatic amino developer to produce a dlye and n is a positive integer from no 6- EmdAGS an inhibitlor of cglor staitn, a non-diffusing p0 y- 3' A color forming photographic emulsion having llletit, compound aving t e stglc ure. (10 duced fogging tendency, comprising a silver halide emul- Q 0H sion having incorporated therein a non-diffusing color @005 coupler capable of reacting with the oxidation product z-[oHfln-NHC oof a primary aromatic amino developer to produce a dye and, as an inhibitor of color stain, a non-difiusing poly- OH meric compound having the structure:

A-CHZ-CH-CH-CH 4 CHzCH-CH--CH- 1 l l l l A on 00011 OOOH 000E o OCH2CHZNHCO where R is selected from the units consisting of where x and y are positive integers from 50 to 2000.

B B 4. A color-forming photographic emulsion having re- VVH (l3A my a, d uced fogging tendency, comprising a silver halide emul- E g V i SlOIl having lncorporated therein a non-diifusing color COOH, oo rit COOH coupler capable of reacting With the oxidation product A of a primary aromatic amino developer to produce a dye and, as an inhibitor of color stain, a non-diliusing polymeric compound having the structure:

-OH CH*GU CH Cllz*CH-CHCH- maomoamnoo-G and where x and y are positive integers from 50 to 2000.

5. A color-forming photographic emulsion having reduced fogging tendency, comprising a silver halide emul- (Labw sion having incorporated therein a non-diffusing color coupler capable of reacting with the oxidation product of a primary aromatic amino developer to produce a dye and, as an inhibitor of color stain, a non-diffusing poly- A is selected from the class consisting of hydrogen, alkyl meric compound having the structure:

l coon radicals and halogen radicals, B is selected from the where x and y are positive integers from 50 to 2000.

2,816,028 13 14 6. A color-forming photographic emulsion having reof a primary aromatic amino developer to produce a dye duced fogging tendency, comprising a silver halide emuland, as an inhibitor of color stain, a non-diffusing polysion having incorporated therein a non-diffusing color meric compound having the structure:

coupler capable of reacting with the oxidation product where x and y are positive integers from 50 to 2000.

No references cited. 

1. A COLOR-FORMING PHOTGRAPHIC EMULSION HAVING REDUCED FOGGING TENDENCY, COMPRISING A SILVER HALIDE EMUL SION HAVING INCORPORATED THEREIN A NON-DIFFUSING COLOR COUPLER CAPABLE OF REACTING WITH THE OXIDATION PRODUCT OF A PRIMARY AROMATIC AMINO DEVELOPER TO PRODUCE A DYE AND, AS AN INHIBITOR OF COLOR STAIN, A NON-DUFFUSING POLYMERIC COMPOUND HAVING THE STRUCTURE: 